Added Java CI workflow

.github/workflows/java-ci.yml

@@ -0,0 +1,19 @@
+name: Java CI
+
+on: [push]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up JDK 16
+        uses: actions/setup-java@v2
+        with:
+          java-version: '16'
+          distribution: 'adopt'
+      - name: Validate Gradle wrapper
+        uses: gradle/wrapper-validation-action@e6e38bacfdf1a337459f332974bb2327a31aaf4b
+      - name: Build with Gradle
+        run: ./gradlew build